This invention relates to refrigeration apparatus, and in particular to absorption refrigeration apparatus and the use of solar energy to power same.
There are two main types of refrigeration apparatus commonly in use today. The most frequently encountered apparatus or refrigeration system includes the following elements coupled in seriatim in a refrigerant circuit: a compressor, a condenser, an expansion valve and an evaporator coil. Compressed liquid refrigerant passes through the expansion valve to be vaporized in the evaporator coil. Heat is absorbed by the refrigerant in the evaporator coil as the refrigerant vaporizes, and the heat is subsequently dissipated in the condenser where the vaporized refrigerant is again liquified. This type of refrigeration system may be operated in a reverse cycle, in which case it is called a heat pump. In a heat pump, in effect, the condenser and evaporator coil switch roles, so the heat is absorbed at the location of the condenser and heat is dissipated at the location of the evaporator coil.
The other main type of refrigeration apparatus is the absorption system, in which case no compressor is used. In the absorption system, briefly, a boiler is used to vaporize and motivate the refrigerant, which then passes through a condenser. Liquid refrigerant from the condenser passes through an evaporator/temperature exchanger where the refrigerant vaporizes to absorb heat energy. The vaporized refrigerant is then converted back to the desired liquid state to re-enter the boiler where heat energy applied to the boiler again vaporizes the refrigerant to repeat the cycle.
In the compressor type refrigeration system first described above, it is desirable to add external heat energy to the system where the system is a heat pump and is operated in the reverse mode described above. It has been proposed in the past to use solar collectors to make use of solar energy in the heat pump system. However, this solar energy has only been used indirectly, and usually through intermediate heat exchangers, to improve the efficiency of the heat pump which still must employ a compressor for operation.